My 1987 FAA 61.75 became invalid when I retired and changed my address in 2006, as the UK CAA issued me with a JAR license. I had to apply for 61.75 again. I was not issued with a new 61.75, but it was revalidated and reissued on the new UK License.
I then converted to an EASA license, with a retained UK license. Same numbers but with different letters. I suspected my 61.75 will need revalidating again. Then Brexit.
My plans were affected by COVID-19 regulations so I haven't done anything to revalidate